docs: def fit(self,y_true_cal=None, y_prob_cal=None):
          """ If calibration, then train the calibration of probabilities
  
          Parameters
          ----------
          y_true_cal : array-like of shape = [n_samples], optional default = None
              True class to be used for calibrating the probabilities
  
          y_prob_cal : array-like of shape = [n_samples, 2], optional default = None
              Predicted probabilities to be used for calibrating the probabilities
  
          Returns
          -------
          self : object
              Returns self.
          """
          if self.calibration:
              self.cal = ROCConvexHull()
              self.cal.fit(y_true_cal, y_prob_cal[:, 1])